Bearing Selection

Measure the bearing clearance to determine the correct replacement bearing insert size. There are two methods to measure bearing clearance. Method A gives more reliable results and is preferred.
^ Method A yields measurement from which the bearing clearance can be computed.
^ Method B yields the bearing clearance directly. Method B does not give any indication of bearing run-out.

Method A

Important: Do not mix inserts of different nominal size in the same bearing bore.





^ Measure the crankshaft bearing journal diameter with a micrometer in several places, 90 degrees apart. Average the measurements.
^ Measure the crankshaft bearing journal taper and runout.
^ Install the crankshaft bearing inserts. Tighten the bearing cap bolts to specification.
^ Measure the connecting rod inside diameter in the same direction as the length of the rod with an inside micrometer.
^ Measure the crankshaft main bearing inside diameter with an inside micrometer.
^ Select a set of bearing inserts that will produce the desired clearance.

If the specified clearances cannot be met, the crankshaft journals must be reconditioned and undersized bearing inserts installed.

Method B

Important: Do not mix inserts of different nominal size in the same bearing bore.

^ Clean the used bearing inserts.
^ Install the used bearing inserts.





^ Place a piece of gauging plastic across the entire bearing width.
^ Install the bearing caps.

Notice: In order to prevent the possibility of cylinder block or crankshaft bearing cap damage, the crankshaft caps are tapped into the cylinder block cavity using a brass, lead, or a leather mallet before the attaching bolts are installed. Do not use attaching bolts to pull the crankshaft bearing caps into the seats. Failure to use this process may damage a cylinder block or a bearing cap.

^ Install the bearing cap bolts to specification.

Important: Do not rotate the crankshaft.

^ Remove the bearing cap, leaving the gauging plastic in place. It does not matter whether the gaging plastic adheres to the journal or to the bearing cap.
^ Measure the gauging plastic at the widest point with the scale printed on the gaging plastic package.
^ Remove the gauging plastic.
^ Select a set of bearing inserts that will produce the desired clearance.